1. Field of the Invention
The present invention relates to an endoscope configured to relatively position a plate member to which a member for operating to bend a bendable portion of an endoscope is fixed and a tubular unit in which a fluid flows.
2. Description of the Related Art
For example, the endoscope disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2000-51148 includes a positioning mechanism which relatively positions a plate member to which a member for operating to bend a bendable portion of the endoscope is fixed and a tubular unit in which a fluid flows. The positioning mechanism has a cylindrical main body member. The main body member has a distal end portion on which a proximal end portion of a bending prevention portion of the endoscope is externally mounted and a proximal end portion on which a distal end portion of a holding casing disposed on an operation portion of the endoscope is externally mounted. For example, the plate member is manufactured by die casting so as to ensure the strength of the plate member. The plate member has a distal end portion fixed to the proximal end portion of the main body member with screws. The tubular unit is fixed to the main body member through a branched tube member.
This branched tube member has one distal end portion and two proximal end portions formed in a bifurcated shape. The branched tube member couples a treatment instrument insertion tube portion which is coupled to the distal end portion of the branched tube member to a mouth ring member which is coupled to a first proximal end portion of the branched tube member, and forms a path to a treatment instrument insertion port portion. The branched tube member couples the treatment instrument insertion tube portion to the tubular unit coupled to a second proximal end portion of the branched tube member.
In general, in the endoscope, the bending operation portion is operated with a left hand while grasping the endoscope with the left hand. At this time, a treatment instrument inserted from the treatment instrument insertion port portion into the inside of the endoscope is operated with a right hand. The bending operation portion and the treatment instrument insertion port portion are disposed in consideration of this graspability and two types of operability. More specifically, the bending operation portion is disposed on a right side surface of the endoscope when viewed from an operator who grasps the endoscope, while the treatment instrument insertion portion is disposed between the right side surface and a back surface of the endoscope when viewed from the operator. In this manner, the bending operation portion and the treatment instrument insertion portion are positioned relative to each other. For this reason, the plate member and the tubular unit are positioned based on the positional relationship between the bending operation portion and the treatment instrument insertion port portion described above. Therefore, the branched tube member, the treatment instrument insertion tube portion, and the mouth ring member are disposed on an obverse surface side of the plate member. The tubular unit extends from the obverse surface side to the reverse surface side of the plate member through a lengthwise-direction recess portion disposed in a distal end of the plate member. The lengthwise-direction recess portion is disposed along a lengthwise direction of the plate member so as to penetrate through the plate member in its thickness direction. In this manner, the branched tube member, the treatment instrument insertion tube portion, and the mouth ring member are disposed on the opposite side of the plate member to the tubular unit.